This invention relates generally to the preparation of alpha-olefins from internal or vinylidere olefins and more specifically to a process to ethenolize internal olefins and isomerize/ethenolize vinylidenes to vinyl olefins using a B.sub.2 O.sub.3 modified Re.sub.2 O.sub.7 on Al.sub.2 O.sub.3 catalyst.
The ethylene chain growth process for producing alpha-olefins (vinyl olefins) using triethylaluminum followed by olefin displacement as practiced commercially can produce olefins containing from 4 up to 30 or more carbon atoms. Although mainly alpha-olefins are produced, some vinylidene and internal olefins also result. These olefin by-products are generally less useful than alpha-olefins and in some applications, such as the production of sulfonic acids for detergents, vinylidene olefins form tertiary mercaptans which are very difficult to oxidize to sulfonic acids. Separation of such olefins by distillation is difficult. We have discovered a novel process for upgrading .alpha.-olefin mixtures containing such olefins to convert the vinylidene and internal olefins to .alpha.-olefins without any significant isomerization of .alpha.-olefins.
U.S. Pat. No. 3,785,956 discloses the disproportionation of a feed composed of ethylene and branched and linear olefins with a catalyst such as rhenium oxide on alumina while maintaining the conversion of the linear olefins within the range of about 30-50 percent. It has been reported by Xiaoding et al., J. Chem. Soc. Farady Trans. 1, 1986, 82, 1945-1953 that Re.sub.2 O.sub.7 /Al.sub.2 O.sub.3 B.sub.2 O.sub.3 -MR.sub.4 (where M=Sn or Pb and R=alkyl) catalysts can be used for the methathesis of alkenes, especially functionalized alkenes such as methyl oleate. This catalyst system is not useful in the upgrading ethenolysis of alpha-olefin mixtures because of its strong isomerization activity for alpha-olefins.